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Priority claimed from GB8615805Aexternal-prioritypatent/GB2192005B/en
Application filed by Dyno Industrier AsfiledCriticalDyno Industrier As
Publication of MY102695ApublicationCriticalpatent/MY102695A/en
UREA- FORMALDEHYDE RESINS WHICH MAY BE CURED TO GIVE PRODUCTS HAVING A LOW TOTAL EXTRACTABLE FORMALDEHYDE CONTENT ARE PREPARED BY THE FOLLOWING PROCESS: (i) AQUEOUS 30- 50% FORMALDEHYDE AND UREA ARE MIXED IN A FORMALDEHYDE: UREA MOLAR RATIO OF 2- 3:1 AT pH 6- 11, (ii) THIS MIXTURE IS HEATED TO AT LEAST 50?C, PREFERABLY TO AT LEAST OR ORGANIC ACIDIS ADDED TO BRING THE MIXTURE TO pH 0.5- 3.5, (iv) THE MIXTURE IS HEATED AT A TEMPERATURE BETWEEN 80?C, AND THE REFLUX TEMPERATURE, PREFERABLY FOR 15 MINUTES TO 1 HOUR, (v)KEEPING THE TEMPERATURE AT OR ABOVE 80?C, A BASE IS ADDED TO BRING THE MIXTURE TO pH 6.5- 9 AND (vi) UREA IS ADDED UNTIL THE FORMALDEHYDE: UREA MOLAR RATIO IS WITHIN THE RANGE 0.8- 1.8:1.IN A MODIFICATION OF THE PROCESS SOLID PARTICULATE RESINS ARE OBTAINED BY REACTING THE MIXTURE FROM STEP (v) WITH UREA AT A pH BELOW 7 TO INCREASE THE VISCOSITY THEREOF, ADDING A BASE UNTIL THE MIXTURE REACHES A pH OF 6.5- 9 AND DEHYDRATING THE RESULTING MIXTURE.
MYPI87002022A1986-06-271987-09-28Process for the preparation of urea-formaldehyde resins.
MY102695A
(en)